diff --git a/cryptography/hazmat/bindings/openssl/pem.py b/cryptography/hazmat/bindings/openssl/pem.py
index 00f0dc3..cef7839 100644
--- a/cryptography/hazmat/bindings/openssl/pem.py
+++ b/cryptography/hazmat/bindings/openssl/pem.py
@@ -29,6 +29,15 @@
 EVP_PKEY *PEM_read_bio_PrivateKey(BIO *, EVP_PKEY **, pem_password_cb *,
                                   void *);
 
+int PEM_write_bio_PKCS8PrivateKey(BIO *, EVP_PKEY *, const EVP_CIPHER *,
+                                  char *, int, pem_password_cb *, void *);
+
+int i2d_PKCS8PrivateKey_bio(BIO *, EVP_PKEY *, const EVP_CIPHER *,
+                            char *, int, pem_password_cb *, void *);
+
+EVP_PKEY *d2i_PKCS8PrivateKey_bio(BIO *, EVP_PKEY **, pem_password_cb *,
+                                  void *);
+
 int PEM_write_bio_X509_REQ(BIO *, X509_REQ *);
 
 X509_REQ *PEM_read_bio_X509_REQ(BIO *, X509_REQ **, pem_password_cb *, void *);